Slack

Slack for fancy-flow — as four imported, versioned packages, one per runtime. Not vendored source: a copy cannot be upgraded, and third-party APIs change.

The ui package is the editor surface and is React on every host — a PHP or Python project installs it and its own runtime package, and never the js one.

What it costs you

One dependency: @particle-academy/fancy-connector-core (or particle-academy/fancy-connector-core on Composer), which the js and php packages pull in themselves. The Python package has zero runtime dependencies.

No Slack SDK. Plain HTTP, deliberately: a vendor SDK is third-party code subject to the kit's full approval bar, and one per provider is hundreds of dependencies nobody is tracking.

Setting it up

Everything below is generated from provider/manifest.json, so it cannot disagree with what the packages do.

Credentials

A Slack connection holds 4 values.

Two kinds of value, and mixing them up matters. A provider credential is ONE value for the whole installation — an OAuth app's client secret serves every connected account. An account credential is one per connected account. A host that stores the second where it stores the first lets one account's credentials reach another's.

Authorising

Slack uses OAuth2 (authorization_code). The package DECLARES the exchange; the HOST performs it — a consent screen needs a browser, a redirect URI and somewhere to persist the result, and all three belong to the host.

• Authorize URL — https://slack.com/oauth/v2/authorize
• Token URL — https://slack.com/api/oauth.v2.access
• Scopes — chat:write
• Access token lifetime — 43200 seconds (12 hours). A host that never refreshes works all afternoon and is broken by morning.

The refresh tokens ROTATE, and they are single use. Every refresh returns a new one and spends the one submitted, so replaying a spent token revokes the ENTIRE grant — the user is signed out, with nothing in the failure that says why.

Two consequences, both of which a host gets wrong by default:

1. Do not RETRY a failed refresh with the same token. A response that arrived but was not persisted — a crash between the reply and the write — turns the reflexive retry into a replay.
2. Do not refresh CONCURRENTLY. Two workers refreshing at once means one of them replays.

Persist the returned token before using the access token it came with.

The estate

Slack has a test estate on the same host, reached with credentials from a SEPARATE test account you register. Selecting sandbox mode uses those credentials.

Install the app into a dedicated development workspace or Slack developer sandbox. Messages are real inside that workspace, but its users and data are separate from production. Developer sandboxes expire by default and have feature and integration limits.

What it can do

Actions

message_post — Slack message

Post a text message to a Slack channel or conversation.

POST /api/chat.postMessage · unsafe to replay — a retried durable run does it TWICE

Run it before you have credentials

Every operation ships a faker, whether or not Slack has a sandbox. Set a node's mode to fake and it returns the shape Slack actually publishes — the same field names, deterministically — so you can wire the downstream nodes before touching an account, a key, or a network.

This repository is generated

provider/ is the source. Everything under packages/ is emitted from it and must not be hand-edited — CI regenerates and diffs on every push, and the next protocol sync destroys anything it finds. See AGENTS.md.

Two namespaces, which do not match on purpose

The repo is github.com/Fancy-Friends/slack; the packages publish under particle-academy. Nothing derives one from the other — the names come from weaver's friends.json and nowhere else.

Licence

MIT.